def swing(party1, party2, year, former_year = -999, printout = True) :
# This analysis prints an ordered list of swings from party1 to party2 in a given
# election, with respect to the previous election. Only seats contested in both
# elections are counted.
#
# The swing is defined as half the change between the score differences of the parties
# from the first election to the second one
#
# Get the previous election year
if printout :
print
print '-------------------------------------------------------------------------------------------------'
print 'Starting printout of swings from',party1,"to",party2,'in',year
print '-------------------------------------------------------------------------------------------------'
print
#
if former_year == -999 :
former_year = str(outputdatabase["elections"][outputdatabase["elections"].index(int(year))-1])
year = str(year)
former_year = str(former_year)
if args.debug : print former_year, year
swings = []
for constituency in outputdatabase :
if constituency == "elections" : continue
# Was it contested in both elections?
if not (outputdatabase[constituency].has_key(year) and \
outputdatabase[constituency].has_key(former_year) ) :
continue
# Have to see if the parties both contested the constituency in both elections
passedchecks = True
for election in [former_year,year] :
parties_in_year = []
for result in possibleresults() :
parties_in_year.append(outputdatabase[constituency][election][result]["party"])
if not (party1 in parties_in_year and party2 in parties_in_year) :
passedchecks = False
if not passedchecks : continue
# OK they did, carry on now
if args.debug :
niceprint(constituency,outputdatabase)
party1_scores = []
party2_scores = []
# This loop works because each party only has one entry per seat per year
for election in [former_year,year] :
for result in possibleresults() :
if party1 == outputdatabase[constituency][election][result]["party"] :
party1_scores.append(outputdatabase[constituency][election][result]["vote"])
elif party2 == outputdatabase[constituency][election][result]["party"] :
party2_scores.append(outputdatabase[constituency][election][result]["vote"])
# The percentage swing
if args.debug : print constituency, outputdatabase[constituency][year]
thisswing = 100.0*(party2_scores[1]-party1_scores[1])/(outputdatabase[constituency][year]["electorate"]*outputdatabase[constituency][year]["turnout"]) - \
100.0*(party2_scores[0]-party1_scores[0])/(outputdatabase[constituency][former_year]["electorate"]*outputdatabase[constituency][former_year]["turnout"])
# The absolute swing
thisswing_abs = (party2_scores[1]-party1_scores[1]) - (party2_scores[0]-party1_scores[0])
# The percentage majority at the previous election
thismajority = 100.0*(party2_scores[0]-party1_scores[0])/(outputdatabase[constituency][former_year]["electorate"]*outputdatabase[constituency][former_year]["turnout"])
swings.append((thisswing/2.,thisswing_abs/2.,thismajority,constituency))
#
# Now print it out
#
swings.sort()
if printout :
totalvoteswing = 0
avgpercswing = 0
print '-------------------------------------------------------------------------------------------------'
print "{:<35}".format("Constituency"), "{:^20}".format("Percentage swing"), "{:^20}".format("Absolute swing"), "{:^20}".format(str(year)+" majority")
print '-------------------------------------------------------------------------------------------------'
for swing in swings :
print "{:40}".format(swing[3]),"{:>8.2%}".format(swing[0]), "{:>21}".format(swing[1]), "{:>19.2%}".format(swing[2])
totalvoteswing += swing[1]
avgpercswing += swing[0]
#
avgpercswing /= len(swings)
print
print 'The average swing from',party1,"to",party2,'in',year,"was","{:0.2%}".format(avgpercswing)
print 'The overall vote swing from',party1,"to",party2,'in',year,"was",totalvoteswing
print
print '-------------------------------------------------------------------------------------------------'
print 'Finished printout of swings from',party1,"to",party2,'in',year
print '-------------------------------------------------------------------------------------------------'
print
return swings
def gainbyparty(party, year, former_year = -999, printout = True) :
# This analysis prints an ordered list of votes gained by a party in a given
# election, with respect to the previous election. Only seats contested in both
# elections are counted. At the end, a small printout is also made of the overall
# totals, and the relevance of these votes to the 2015 picture in the seats
#
# Get the previous election year
if printout :
print
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
print 'Starting printout of votes gained by',party,'in',year
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
print
#
if former_year == -999 :
former_year = str(outputdatabase["elections"][outputdatabase["elections"].index(int(year))-1])
year = str(year)
former_year = str(former_year)
if args.debug : print former_year, year
votegains = []
alsoin2015 = 0
totalvotegain = 0
votegainsin2015 = { "Labour" : [], "Conservative" : [], "Lib Dem" : []}
for constituency in outputdatabase :
if constituency == "elections" : continue
# Was it contested in both elections?
if not (outputdatabase[constituency].has_key(former_year) and \
outputdatabase[constituency].has_key(year) ) :
continue
# OK they did, carry on now
if args.debug :
niceprint(constituency,outputdatabase)
party_scores = []
# This loop works because a party only has one entry per seat per year
for election in [former_year,year] :
for result in possibleresults() :
if party == outputdatabase[constituency][election][result]["party"] :
party_scores.append(outputdatabase[constituency][election][result]["vote"])
if not len(party_scores) == 2 : continue
# The votes gaines
thisgain_abs = party_scores[1]-party_scores[0]
# The percentage majority at the previous election
thismajority = getmargin(constituency,year,outputdatabase)
formermajority = getmargin(constituency,former_year,outputdatabase)
votegains.append((thisgain_abs,thismajority,formermajority,constituency,
outputdatabase[constituency][year]["winner"]["party"],
outputdatabase[constituency][former_year]["winner"]["party"]))
totalvotegain += thisgain_abs
if outputdatabase[constituency].has_key('2015') :
alsoin2015 += 1
for winner2015 in ['Labour','Conservative','Lib Dem'] :
if outputdatabase[constituency]['2015']["winner"]["party"] in [winner2015] :
votegainsin2015[winner2015].append(thisgain_abs)
#
# Now print it out
#
votegains.sort()
if printout :
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
print "{:<35}".format("Constituency"), "{:^20}".format("Votes Gained"), "{:^20}".format(str(year)+" winner"), "{:^20}".format(str(year)+" majority"), "{:^20}".format(str(former_year)+" winner"), "{:^20}".format(str(former_year)+" majority")
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
for votegain in votegains :
print "{:40}".format(votegain[3]),"{:>8}".format(votegain[0]), "{:>21}".format(votegain[4]), "{:>19.2%}".format(votegain[1]), "{:>21}".format(votegain[5]), "{:>19.2%}".format(votegain[2])
#
print
print 'There were',len(votegains),'contituencies in common between the',year,'and',former_year,'elections'
print alsoin2015,'of these also existed in the 2015 election'
print 'The overall vote gain for',party,'in',year,"was",totalvotegain
for winner2015 in ['Labour','Conservative','Lib Dem'] :
print 'The overall vote gain in the',len(votegainsin2015[winner2015]),'seats which the',winner2015,'party still holds in 2015 was',sum(votegainsin2015[winner2015])
print
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
print 'Finished printout of votes gained by',party,'in',year
print '--------------------------------------------------------------------------------------------------------------------------------------------------------'
print
return alsoin2015,totalvotegain,votegainsin2015,votegains
